No abstract

Mifepristone (RU486) is a born-for-woman molecule discovered three decades ago. Unlike those antihypertensive and antipsychotic pharmaceutical blockbusters, this abortifacient offers relatively low profit potential. Current understanding of mechanism of action of mifepristone and its on-going clinical trials are changing our views on the drug beyond its abortifacient scope. Here we briefly review its metabolism and pharmacokinetic properties including its unique enterohepatic circulation, its mechanisms of actions involving antiprogesterone and antiglucocorticoid, growth inhibition of various cancer cell lines, suppression of invasive and metastatic cancer potential, downregulation of Cdk2, Bcl-2, and NF-kappa B, interference of heterotypic cell adhesion to basement membrane, and cell migration. We comprehensively analyze recent results from preclinical and clinical studies using mifepristone as an anticancer drug for breast, meningioma, and gliomas tumors in the central nervous system, prostate cancer, ovarian and endometrial cancer, and gastric adenocarcinoma. Although mifepristone has more benefits for global public health than we originally thought, its effect as a postmetastatic chemotherapeutic agent is limited. Nonetheless, owing to its unique safe, metabolism and other pharmacological properties, metapristone (the primary metabolite of mifepristone) may have potential for cancer metastatic chemoprevention.

Adhesion of circulating tumor cells (CTCs) to vascular endothelial bed becomes a crucial starting point in metastatic cascade. We hypothesized that nitric oxide (NO) may prevent cancer metastasis from happening by its direct vasodilation and inhibition of cell adhesion molecules (CAMs). Here we show that S-nitrosocaptopril (CAP-NO, a typical NO donor) produced direct vasorelaxation that can be antagonized by typical NO scavenger hemoglobin and guanylate cyclase inhibitor. Cytokines significantly stimulated production of typical CAMs by the highly-purified human umbilical vein endothelial cells (HUVECs). CAP-NO inhibited expression of the stimulated CAMs (particularly VCAM-1) and the resultant hetero-adhesion of human colorectal cancer cells HT-29 to the HUVECs in a concentration-dependent manner. The same concentration of CAP-NO, however, did not significantly affect cell viability, cell cycle and mitochondrial membrane potential of HT-29, thus excluding the possibility that inhibition of the hetero-adhesion was caused by cytotoxicity by CAP-NO on HT-29. Hemoglobin reversed the inhibition of CAP-NO on both the hetero-adhesion between HT-29 and HUVECs and VCAM-1 expression. These data demonstrate that CAP-NO, by directly releasing NO, produces vasorelaxation and interferes with hetero-adhesion of cancer cells to vascular endothelium via down-regulating expression of CAMs. The study highlights the importance of NO in cancer metastatic prevention.

Mifepristone (RU486) is marketed and used widely by women as an abortifacient, and experimentally for psychotic depression and anticancer treatments. After administration, metapristone is found to be the most predominant metabolite of mifepristone. We hypothesized that adhesion of circulating tumor cells (CTCs) to vascular endothelial bed is a crucial starting point in metastatic cascade, and that metapristone can serve as a cancer metastatic chemopreventive agent that can interrupt adhesion and invasion of CTCs to the intima of microvasculature. In the present study, we modified the synthesis procedure to produce grams of metapristone, fully characterized its spectral properties and in vitro cellular activities, including its cytostatic effects, cell cycle arrest, mitochondrial membrane potential, and apoptosis on human colorectal cancer HT-29 cells. Metapristone concentration dependently interrupted adhesion of HT-29 cells to endothelial cells. Metapristone may potentially be a useful agent to interrupt metastatic initiation.

Ursolic acid (UA) is a naturally bioactive product that exhibits potential anticancer effects. The relatively safe and effective molecule intrigued us to explore a way to further improve its anti-cancer activity and tumor-targeting specificity. In the present study, a series of structural modifications of UA was achieved, which resulted in significant increase in growth inhibition on various cancer cell lines with minimal effects on normal cells. The leading molecule US597 (UA-4) caused depolarization of mitochondrial membrane potential, cell arrest in G0/G1 phase and apoptosis/necrosis in a dose-dependent manner. Structural docking suggested that the carbon chains of the modified UA derivatives compete strongly with glucose for binding to glucokinase, the key glycolysis enzyme presumably active in cancer cells. The combination of 2-deoxy-D-glucose (2-DG) and UA-4 induced cell cycle arrest in G2/M phase, promoted caspase-dependent cell death, reduced hexokinase activity, aggravated depletion of intracellular ATP, decreased lactate production and synergistically inhibited cancer cell growth in vitro (HepG2) and in vivo (H22). Collectively, our findings suggest that the structural modification enhances efficacy and selectivity of UA, and the combination of UA-4 with 2-DG produces synergistic inhibition on hepatoma cell proliferation by dual targeting of apoptosis and glycolysis.

BACKGROUND: This study was aimed at establishing a sensitive and specific isolation, characterization, and enumeration method for living circulating tumor cells (CTCs) in patients with colorectal carcinoma. METHODS: Quantitative isolation and characterization of CTCs were performed through a combination of immunomagnetic negative enrichment and fluorescence-activated cell sorting. Isolated CTCs were identified by immunofluorescence staining. The viability and purity of the sorted cells were determined by flow cytometry. Blood samples spiked with HCT116 cells (range, 3-250 cells) were used to determine specificity, recovery, and sensitivity. The method was used to enumerate, characterize, and isolate living CTCs in 10 mL of blood from patients with colorectal carcinoma. RESULTS: The average recovery of HCT116 cells was 61% or more at each spiking level, and the correlation coefficient was 0.992. An analysis of samples from all 18 patients with colorectal carcinoma revealed that 94.4% were positive for CTCs with an average of 33 6 24 CTCs per 10 mL of blood and with a diameter of 14 to 20 lm (vs 8-12 lm for lymphoma). All patients were CD47 1 , with only 4.3% to 61.2% being CD44 1 . The number of CTCs was well correlated with the patient TNM stage and could be detected in patients at an early cancer stage. The sorted cells could be recultured, and their viability was preserved. CONCLUSIONS: This method provides a novel technique for highly sensitive and specific detection and isolation of CTCs in patients with colorectal carcinoma. This method complements the existing approaches for the de novo functional identification of a wide variety of CTC types. It is likely to help in predicting a patient's disease progression and potentially in selecting the appropriate treatment. Cancer 2015;121:3036-45.

Hepatocellular carcinoma (HCC) is the second leading cancer death because of its high metastasis and drug resistance. Regorafenib was newly approved by FDA for HCC treatment, but its resistance is not understood. The unique isomerase Pin1 is critical for HCC development, but its role in metastasis and drug resistance is unknown. Here we generated Regorafenib-resistant HCC cells and found that they exhibited enhanced tumor invasion and metastasis in vitro and in vivo, and elevated Pin1 levels. Furthermore, Pin1 was highly overexpressed and closely related to the EMT in human HCC tissues. Depletion or overexpression of Pin1 correspondingly inhibited or promoted HCC cell migration and invasion, with altered expression of EMT-related molecules, Ecadherin and Snail. Significantly, Pin1 interacted with Gli1, a regulator of the EMT, and silencing Gli1 partly blocked Pin1-induced EMT in HCC cells. Moreover, genetic or chemical Pin1 inhibition reversed Regorafenib resistance of HCC with reducing EMT, migration, invasion and metastasis in vitro and in vivo. These results reveal a novel molecular mechanism underlying Regorafenib resistance in HCC, and also provide first evidence that Pin1 inhibitors offer an attractive strategy for treating Regorafenib-resistant HCC.

Recent scientific advances have increased our understanding of the cancer metastatic complexities and provided further impetus for new combination therapies to prevent cancer metastasis. Here, we demonstrated that a combination (HAMPT) of aspirin, lysine, mifepristone and doxycycline can effectively and safely prevent cancer metastasis. The pharmaceutically-formulated HAMPT inhibited adhesion of cancer cells to either endothelial cells or extracellular matrix via down-regulating cell adhesion molecules ICAM-1 and α4-integrin. HAMPT inhibited the cloak effect by activated platelets on cancer cells, thereby interfering adhesion and invasion of cancer cells to the underlying stroma. At the effective concentration, HAMPT induced cancer cells into dormancy with minor inhibition on cell viability. Four-day pretreatment followed by 30-day oral administration of HAMPT (33.5-134 mg/kg) to the mice inoculated with cancer cells produced significant inhibition on cancer metastasis dose-dependently without marked side effects. Fifty-day rat toxicity study with HAMPT at doses (335-1340 mg/kg) 20-fold higher than its therapeutic dose produced no significant toxicity. Interestingly, the acute toxic death could not be reached at the maximum administrable dose (5 g/kg). This proof-of-concept study provides the first conceptual evidence that cancer metastasis can be controlled by using affordable old drugs to restrain circulating tumor cells from gemmating on the metastatic soil without the need for cytotoxicity.